The invention relates to low toxicity tobacco filled smoking articles, and more especially to cigarettes, cigars and/or filled pipes adapted to provide a low proportion of carbon monoxide in the combustion gases.
It has been established for a long time that carbon monoxide constitutes a very poisonous gas, which more particularly damages the cardiac blood vessels, and that a very high proportion of carbon monoxide is contained in the gaseous products of combustion from tobacco. Despite knowledge of this fact, the very numerous and extremely expensive investigations into and attempts at removing toxic substances from gaseous products of combustion of tobacco so far have only succeeded in bringing about a substantial reduction in the nicotine content and the tar content. To date it has not been possible to reduce the carbon monoxide content to a substantial extent. On the contrary, it is especially those filter cigarettes having a low nicotine content, which have a particularly high content of carbon monoxide in the gaseous products of combustion. It has been found that the carbon monoxide can hardly be removed to any extent at all by filters.
However, many other methods have been tried in order to recuce the carbon monoxide content from the gaseous combustion products of tobaccos without, however, leading to success.
Thus, for example, J. H. Terrell and I. Schmeltz investigated modifications in the composition of cigarette smoke by the formation of holes in the cigarette paper and published their results in "Tobacco Science", vol. XIV, 1970, pages 82 to 85. The holes in the cigarette paper act as inlets for additional air which dilutes the cigarette smoke. On the basis of this dilution, they found that there was naturally a reduced proportion of CO per draw in their measurements as compared to the case for one draw on a cigarette which is not externally perforated. The total quantity of CO which is formed on smoking the two different forms of cigarettes was however the same. Attention is drawn, however, to the different phenomena involved; that is to say, cigarettes with perforated cigarette paper release a larger proportion of CO to the atmosphere on smouldering between draws as compared with the inhaled quantity of CO than is the case with normal cigarettes. This is due to the fact that the cigarette with perforated cigarette paper burns substantially shorter per draw than the normal cigarette owing to the bypass air and the resulting lowered degree of suction.
This makes the substantial disadvantage of this previously proposed cigarette with perforated cigarette paper clear, i.e., the smoker, owing to the lesser absolute quantity of smoke per draw, which furthermore is diluted with bypass air, does not breath the desired smoke with an intensive flavor and instead breathes in an uninteresting highly diluted smoke mixture with a neutral flavor. Tests have shown that even ten holes in the cigarette paper have the effect of causing the burning in the smouldering zone not to be noticeably increased by a draw on the cigarette and practically only bypass air is inhaled in such a case.
Furthermore, the periodical "Tobacco Science" vol. XIV, 1970, pages 79 to 81 refers to attempts to modify the composition of the gaseous products of combustion by additives to tobacco. However, practically all of the additives referred to in this periodical resulted in a substantial increase in the CO proportion in the gaseous products of combustion, see the table at the top of page 80. The few other additives, which reduced the CO content, albeit only slightly, had on the other hand the disadvantageous effect that they substantially increased the proportion of toxic substances such as H.sub.2 S, NO, SO.sub.2 and/or HCN.
Since none of these methods reduced the CO content noticeably, or if at all, then only with an increase of other highly toxic smoke components, attempts were made to reduce the production of the CO component by the addition of catalyst precursors which, on combustion, form highly dispersed and very active solid catalysts. See for example, the German patent application No. P 25 18 839 in the name of Victor Brantl.